Bulb assembly

ABSTRACT

A lamp socket assembly has a plastic housing and a transversal flange surrounding the same. Spaced resilient tabs are arranged on the flange for snapping into a cut-out of a reflector. Additional spaced tabs having shoulders at the extended ends thereof are arranged on the flange with spacers provided therebetween. The height of the additional tabs exceeds that of the spacers. A conductive bulb carrier for engaging the base of a bulb from one end of the housing is held between the shoulders and the ends of the spacers. A conductive resiliently mounted plug engages a center electrode of a bulb and urges the bulb into engagement with the conductive bulb carrier.

[ Nov. 27, 1973 BULB ASSEMBLY lnventors: Ernst Merki, Stuttgart; Otto Giirg,

Rutesheim; Joachim Grupp, Esslingen, all of Germany Robert Bosch GmbH, Stuttgart, Germany Filed: May 18, 1972 Appl. No.: 254,419

Assignees Foreign Application Priority Data May 19, 1971 Germany P 21 24 930.9

U.S. Cl. 339/128, 339/176 L, 339/188 C Int. Cl HOlr 13/32 Field of Search 313/318; 339/59 L,

339/61 L, 127 R, 127 C, 128, 176 L, 17 D References Cited UNITED STATES PATENTS 4/1956 Woofter 339/128 Primary ExaminerRudolph V. Rolinec Assistant Examiner-Wm. l-l. Punter Attorney-Michael S. Striker 5 7] ABSTRACT A lamp socket assembly has a plastic housing and a transversal flange surrounding the same. Spaced resilient tabs are arranged on the flange for snapping into a cut-out of a reflector. Additional spaced tabs having shoulders at the extended ends thereof are arranged on the flange with spacers provided therebetween. The height of the additional tabs exceeds that of the spacers. A conductive bulb carrier for engaging the base of a bulb from one end of the housing is held between the shoulders and the ends of the spacers. A conductive resiliently mounted plug engages a center electrode of a bulb and urges the bulb into engagement with the conductive bulb carrier.

13 Claims, 2 Drawing Figures PATENTEB Z 3,775,731

suwenrz Fig. 2

BULB ASSEMBLY BACKGROUND OF THE INVENTION The invention relates to lamp socket assemblies, and particularly to a lamp socket assembly which can be assembled and mounted in an opening of a reflecting surface without the need of additional fastening means.

Various bulb assemblies are already known. Bulb holders or sockets of this type are generally utilized in conjuction with a lamp assembly which includes a reflecting surface. In most instances, the reflecting surface is provided with an opening or a cutout in which the bulb holder or socket may be releasably held with its light emitting portion on the reflecting side of the surface. Such bulb assemblies are mostly used in automobiles and other motor vehicles for providing signals which indicate that the vehicle is about to make a turn or is stopping. Bulb holders of this type are commonly made from plastics since they resist corrosion and simultaneously provide the necessary insulation between the various electrodes of the bulb. When plastic housings are utilized for the holders, it is necessary to simultaneously provide a conducting path for the ground as well as the hot terminal of the bulb.

In one bulb holder of this type, leaf-shaped bevel tabs are diametrically arranged on the holder and engage guide openings in the reflecting surface. Rotation of the housing, and therefore of the tabs once they have passed through the reflecting surface and beyond the guide openings, locks the housing to the surface. However, such a holder is not satisfactory for all applications. In another such known bulb socket, several outwardly elongated tabs are somewhat deformed so that they resiliently engage the rim or edge of a reflector opening. Such engagement arrests the holder and prevents the same from moving. This known embodiment, however, has the disadvantage that the resilient connection of the current carrying and therefore heat forming part makes such holders only suitable for minor sockets in conjunction with bulbs which do not dissipate much power.

Also known are plastic housings which have resilient arms and hooks which engage the rim of a reflector opening. With this known embodiment, a collar is provided on the reflector which holds the bulb socket in the desired position. However, this known construction has the disadvantage that such a collar must be provided, since without the latter the holder takes on a complicated construction which is costly to manufacture. Additionally, with the holder under discussion, the bulb can only be changed from the front side of the reflector since the opening in the reflector is smaller than the dimensions of the bulb. In this connection, modern reflectors are comparatively narrow, so that the removal of the bulbs from the front may damage the reflecting surface. With other known constructions, the bulb can only be removed from the rear side of the reflector because the light assembly lens is rigidly connected with front reflecting sides of the reflector.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a bulb assembly which does not possess the above disadvantages.

It is another object of the present invention to provide a bulb assembly which is simple in construction and economical to manufacture.

It is still another object of the present invention to provide a bulb assembly which permits the bulb to be removed from the rear side of the reflecting surface.

It is a further object of the present invention to provide a bulb assembly which may easily be engaged with a reflecting surface without the need for additional fastening means.

It is still a further object of the present invention to provide an assembly of the type under discussion which also permits changing the bulb from the reflecting surface side of the reflector.

It is yet a further object of the present invention to provide an assembly for mounting bulbs which is reliable, resistant to deterioration due to climatic conditions and which can be assembled in a short period of time.

With the view of achieving the above objects, the present invention for a bulb assembly comprises, in combination, a substantially hollow cylindrical housing at least a portion of which is made from an electrically insulating material for receiving the base of a bulb at one end of said housing. A transversal flange is provided on said housing which surrounds the same and has a supporting surface facing said one end. At least two resilient engaging means are provided on said flange projecting from said supporting surface and arranged to snap into engagement with the edge of a cutout into which said housing is introduced.

According to another important feature of the present invention, additional resilient engaging means are provided which also project from said supporting surface. Conductive carrier means which are engageable with said second resilient means are provided and are arranged to make contact with one of the electrodes of the bulb when mounted in said housing. Electrical contact means are also provided at the other end of said housing for making contact with the other electrode of the mounted bulb.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an exploded view, in perspective, of the bulb holder in accordance with the present invention; and

FIG. 2 is a side elevational view, in cross section showing the bulb holder of FIG. 1 assembled and carrying a bulb.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the Figures, where similar reference numerals have been utilized to identify similar parts throughout, and first referring to FIG. 1, the bulb holder comprises a plurality of separable parts, namely a plastic housing 10, a conductive bulb carrier 11, a conductive plug 12, a helical spring 13 and a transverse holding member 14. These separable parts are independently manufactured and assembled in a manner to be described.

The plastic housing 10 comprises a substantially hollow cylindrical cup-shaped portion 15. The housing 10 is, in accordance with the presently preferred embodiment, advantageously made from an electrically insulating material such as plastic. A transversal flange 16 is arranged around the cup surrounding the same and having a supporting surface 16a which faces one end of the housing 10. An annular face 17 is spaced downwardly of the supporting surface 16a to form a ridge 17a. In the outer periphery of the flange 16 there is provided a rectangular cutout 18.

The housing 10 can be made by injection molding and made from polyamide.

The plastic housing It) is substantially hollow and has a cylindrically formed space 19. Projecting from the supporting surface 16a is a wide locking tab 20 and two narrow locking tabs 21 and 22 which are substantially diametrically opposed from the wide locking tab 20. The interiorly facing surfaces of all the locking tabs form extensions of the cylindrical opening 19 in the cup 15. Provided on the top of each locking tab is a locking shoulder 23 which has a triangular or bevelled upper portion and retaining surface 24 which is substantially parallel to the supporting surface 16a. The tabs 20, 21 and 22 are, in the present embodiment, made integral with the plastic housing 10 and are resilient so that they may be somewhat flexed in radial directions by applying inward forces to the locking snaps 23.

Spaced between the wide locking tab 20 and the narrow locking tab 22 is a spacer 25, while a spacer 26 is positioned between the wide locking tab 20 and the narrow locking tab 21. The spacers 25 and 26 are substantially at the same radial distance as are the locking tabs so that their inwardly facing surfaces likewise form extensions of the inner surface of the opening 19. Each of the spacers 25 and 26 is provided with a cylindrical cut out section 27 and 28 respectively, defining recesses which receive the conductive bulb carrier 11, as will hereafter be described.

The tabs 20, 21 and 22 extend above the surface 160 so that the retaining surfaces 24 are positioned a predetermined distance above the supporting surface. On the other hand, the extended ends of the spacers 25 and 26 are positioned a distance above the supporting surface 16a which is slightly less than said predetermined distance. In this manner, as will hereafter be described, the locking tabs and the spacers cooperate to rigidly secure the conductive bulb carrier 11 to the plastic housing Ml.

Further provided on the conducting surface 16a are five resilient tabs 29 which are spaced from one another and are, in the'presently preferred embodiment, positioned at the same radial distance from the axis of the housing. Each resilient tab is also integral with the plastic housing 10 and has an upper protuberance 39 which is formed by an upper surface 31 and a lower surface 32. The upper surface 31 is inclined upwardly and inwardly while the lower surface 32 is inclined downwardly and inwardly. With this construction, the resilient tabs 29 first are deformed inwardly and then snap outwardly when forced past the edge of a relatively thin plate, such a reflector opening edge.

The conductive bulb carrier 11 is made from sheet metal and includes an annular ring 33 from which are suspended in one direction two diametrically opposite supporting arms 34 which are provided at their lower ends with cutouts 35. The supporting arms 34 project from the inside periphery of the ring 33. Also projecting from the inside periphery are two projections 36 and 37 which project inwardly. Projecting from the outer periphery of the ring 33 is a ground lug 38 which projects in the same direction as the supporting arms 34, approximately perpendicularly to the ring 23. Provided at the end of the ground lug 38 is a connecting tab 39 which is suitable for connection to an electrical conductor in a well known manner. The connecting tab 39 is so configurated that it can form the male contact of a plug commonly used in motor vehicles (not shown).

The conductive plug 12 is similarly made from sheet metal and is provided with a connecting tab 40 similar to tab 39. Again, the connecting tab 40 may be either soldered to an electrical lead or it may be inserted into a plug to which the electrical conductor is connected. To each side of the conductive plug 12 is a projecting tab 41, which serves to limit the movement of the plug, as will hereafter be described. The plug 12 is also provided with two rectangilar cutouts 49 at one end thereof. The transverse holding member 14 comprises a plastic plate which has an H-forn'ied opening 42 and rectangular end bars 56. The opening 42 is arranged to receive the end of the conductive plug 12 which bears the cutouts 49 so that the bars 56 become lodged inside the cutouts 49 to thereby form a locking engagement between these two elements.

Referring now to both FIGS. 1 and 2, the assembly of the bulb holder will now be described. The conductive bulb carrier 11 is angularly positioned so that when it is axially aligned with the plastic housing 10, the projections 36 and 37 are positioned intermediate the locking tabs 21 and 22 and the locking tab 24 and the spacer 26 respectively. In this manner, the projections 36 and 37 do not come into contact with any of the projecting members which extend from the surface 16a. The conductive bulb carrier 11 is then pressed against the locking tabs 20, 21 and 22 so that the inside edge of the ring 33 bears against the exterior sloping or bevelled surfaces of the locking snaps 23 to thereby force the locking tabs to be deflected or deformed radially inwardly until the inside edge of the ring 33 passes over the locking shoulders 23. Once such passage is fully achieved, the lower surface of the ring 33 comes to bear on the upper projecting ends of the spacers 25 and 26 while the locking tabs 20, 21 and 22 spring back outwardly and engage the upper surface 11b of the ring 33 with the retaining surfaces 24. In this manner, the ring 33 is rigidly fixed and prevented from moving in axial directions of the housing 10. Also, because of the projections 36 and 37, which are positioned between the projecting members as described above, the ring 33 is also prevented from moving angularly. When such conductive bulb carrier 11 engagement is achieved, the ground lug 38 projects past the flange 16 by passing through the rectangular cutout 18 in the direction of the cap 15. Also, when so engaged, the supporting arms 34 are positioned interiorly of the spacers 25 and 26 and are lodged within the cut out sections 27 and 28 of the latter. In this mounted position of the conductor bulb carrier 11, the interiorly facing surface of the locking tabs 20, 21 and 22 and the inner surfaces of the supporting arms 35 are substantially flush with the interior surface of the cutout or open cylindrical space 19 which extends into the cup 15.

Referring to FIG. 2, the cup 15 at the end facing away from the supporting surface 16a is provided with an inwardly projecting portion 48 which is integral with the housing 10. The projecting portion 48 is provided with a slot 47 through which the plug 12, in the form of a flat plate, passes through. Therefore, after the conductive bulb carrier 1 1 has been mounted, the conductive plug 12 is inserted through the slot 47 from the top towards the bottom as viewed in FIG. 2. The dimension of the slot 47 is selected so that the plug 12 can pass therethrough but the projecting tabs 41 cannot so that the plug 12 can only be partly passed through the slot 47. The helical spring 13 can now be placed into the cap 15 through its lower end, and through the ring 33, until it abuts with the annular shoulder serving as abutment means for the spring and located in the region of the inwardly projecting portion 48. The helical spring 13 is now compressed and the plastic plate or transverse holding member 14 is forced ont the conductive plug 12 so that it engages the latter in the cutouts 49 as well as the lower turns of the helical spring 13 and maintains the latter compressed. With this arrangement, the helical spring 13 biases the conductive plug 12 in a downward direction, as viewed in FIG. 2, through the pressure applied on the plate 14. With this arrangement, it is clear that the conductive plug 12 can move between two axial positions. An upper axial position is determined by the abutment of the plate 14 with the inwardly projecting portion 48. A lower axial position results when the projecting tabs 41 come into contact with the inwardly projecting portion 48. Between these two limiting positions, the conductive plug 12 may move, although it is biased in a downward direction so that it normally rests in its lower position when no bulb is secured in the holder. When a base 50 of a bulb 43 is inserted into the space 19, it is initially inserted so that the guide 51 of the base 50 of the bulb moves axially along the supporting arm 34. When the bulb has been fully inserted into the opening 19, thereby forcing the conductive plug 12 to move to its upper axial position, the bulb is rotated so that the guide pins 51 become angularly aligned with the cutouts 35. At such time, the bulb 33 can be released and the spring biased conductive plug 12 will force the bulb 43 to move in a downward direction so that the guide pins 51 engage the cutouts 35. In this position, the guide pins 51, which are integral with the base 50 and form one electrode of the bulb 43, are placed in contact with the ground lug 38, while the center electrode 50a of the bulb 43 is in abutment with the conductive plug 12, the electrode 50a forming the other electrode of the bulb.

The inwardly projecting portion 48, which is not visible in FIG. 1, resiliently supports the center electrical contact which makes contact 12 with the center electrode 50a.

The supporting arms 35, as well as the spacers 25 and 26 are invisible in FIG. 2. However, as explained above, the spacers 25 and 26 would normally project from the surface 16a to the surface 11a of the ring 33.

By so biasing the bulb in a downward direction, as described above, the bulb 43, engaging the supporting arms 34 of the rigidly fixed ring 33, is prevented from falling out of the holder. A female connector or plug 46 is forced onto the upper connecting portion of the conductive plug 12, as suggested above, the plug 46 being connected to a cable 45. The ground lug 38 and the cable 45 can now be connected to the poles of a battery which energizes the bulb 43.

If such a bulb holder is to be used in connection with a reflector 53 which is electrically conductive, it is possible to replace the ground plug 38 with a spring lug (not shown), which is forced into contact with the reflector 53 when the ring 33 is mounted as described above. In this case, no additional wires need be connected to the ground lug, rather the electrical circuit is completed directly through the conductive reflector.

The advantage of the above-described lamp holder or bulb holder consists mainly in that it is mountable on the refelecting surfaces without the necessity of utilizing additional fastening means, e.g. without screws or spring like projections in the reflecting surface or separately provided fastening means which are connected to the housing itself. Additionally, with the abovedescribed embodiment, the resilient tabs 29 cannot undesirably disengage from the supporting surface 16a and therefore provide a good fastening connection thereto. Additionally, the electrical contacts 11 and 12 which must contact the various electrodes of the bulb are simply and quickly mounted into the housing and do not require further elaborate fastening means. The mounting of the electrical contacts is therefore reliable and does not permit the same to become disengaged from the housing.

According to a further advantageous feature of the present invention, a protective cover 44 is provided which prevents dirt as well as the elements from coming into contact with the electrical contacts. The protective cover 44 has a lower portion, as viewed in FIG. 2, with an annularly shaped disk 55 which is adapted to engage the flange 16 by snapping over the outer periphery and engaging the annular surface 17 thereof. The lower surface of the disk 55 is substantially coplanar with the supporting surfaces 16a so that both of these surfaces rest against the non-reflecting surface of the reflector 53 when the holder is mounted therein. When the bulb is to be changed, the entire housing 10 as well as the protective cover 44 can easily be separated from the reflector 53 by placing a coin or a tool, such as a screwdriver, underneath the disk 55 and prying it up against the reflector 53. Such action causes the resilient tabs 29 to bend inwardly in response to the relative movement of the flange 16 with respect to an edge 54 of a cutout in the reflector 53.

When such lamp or bulb holder-lamp assembly is not provided with a covering which protects the holder from the outside, as described above, it may be advantageous that the housing be provided with a rele'asably engaging cap which mates with the portion of the housing to cover the portion of the latter which has a slot for the conductive plug 12. In this manner, dirt is prevented from entering the slot where it would otherwise arrest the axial movements of the plug 12 which have been described above. When high requirements are made to seal the housing against moisture, e.g., water spray or heavy rain, then in accordance with a further of the present invention, the entire cup or the above selected regions, can be further protected by an additional protecting cover.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of bulb holders differing from the types described above.

While the invention has been illustrated and described as embodied in a bulb for a bulb assembly which does not require additional fastening elements to connect the same to a reflecting surface and wherein the electrical contacts are securely mounted in a plastic housing, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can be applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and therefore such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. in a lamp socket assembly, a combination comprising a housing at least a portion of which is made from an electrically insulating material, said housing comprising a substantially cylindrical hollow portion having an open end for receiving the base of a bulb, a transversal flange surrounding said cylindrical portion and hav ing a supporting surface around said open end, at least two first resilient engaging means projecting from said supporting surface so as to engage the edge of a cutout into which said housing is introduced, and second resilient engaging means projecting from said surface; and electrically conductive carrier means engageable with said second engaging means and establishing electrical contact with one of the electrodes of the bulb whose base is received in said cylindrical portion.

2. A combination as defined in claim 1, wherein said flange is provided at its supporting surface with an annular face removed a predetermined distance from said supporting surface to thereby form an annular ridge in the region of periphery of said flange.

3. A combination as defined in claim 1, wherein said flange has a cut-out, and said conductive carrier means has a lug extending from one side of said flange to the other side thereof through said cut-out.

4. A combination as defined in claim 3, wherein said cut-out has a rectangular shape.

5. A combination as defined in claim I, further cornprising protective cap means for covering said other end of said housing and releasably connected to the latter.

6. A combination as defined in claim 5, wherein said flange has an annular face on the side of said supportin g surface, said protective cap including resilient snapping means which snap over said flange and engage said annular face to thereby lock said cap to said housing.

7. A combination as defined in claim 1, wherein said second resilient engaging means comprises at least two spaced tabs projecting from said supporting surface, each tab having a locking shoulder at its projecting end at a predetermined distance above said supporting surface; said housing further comprising at least two spacers in the region of said tabs and projecting from said supporting surface a distance approximately equal to said predetermined distance; and said conductive carrier means comprising a substantially flat annular ring operative to radially deflect said spaced tabs in response to passage of said ring over said locking shoulders and being held by said shoulders in abutment with said spacers once the ring passes the shoulders and is spaced said predetermined distance from said supporting surface.

8. A combination as defined in claim 7, wherein said conductive carrier means further comprises two diametrically opposite supporting arms projecting from said annular ring toward said other end when said ring is held by said spaced tabs and said spacers, each supporting arm having at its projecting end a cutout for engaging a guide pin mounted on the base of the bulb.

9. A combination as defined in claim 7, wherein said spacers are positioned on said supporting surface in the region of said supporting arms of said locked ring, each spacer engaging a respective arm to thereby prevent the latter from being deflected in a radial direction.

10. A combination as defined in claim 1, wherein said cylindrical portion has another end spaced from said open end; and further comprising electrical contact means arranged at the other end of said cylindrical portion and contacting the other electrode of the bulb whose base is received in said cylindrical portion.

11. A combination as defined in claim 10, wherein said electrical contact means comprises a conductive plug movable axially in relation to said other end of said cylindrical portion; limiting means for confining said conductive plug to axial movement between two positions; biasing means for urging said conductive plug to one of said positions, said conductive plug being held in a further position intermediate said two positions in response to engagement of said conductive plug with said other electrode of the bulb whose base is received in said cylindrical portion.

12. A combination as defined in claim 11, wherein said housing includes abutment means at said other end of said cylindrical portion; said limiting means including a transverse holding member connected to said conductive plug, and said biasing means comprising a helical spring compressed between said abutment means and said transverse holding member.

13. A combination as defined in claim 11, wherein said conductive plug is in the shape of a flat plate having spaced projections, and wherein said limiting means comprises a central slotted portion made from electrically insulating material, said plate being slidably mounted in the slot of said slotted portion. and said projections permitting said plate to slide between two axial positions in said slot.

UNITED STATES PATENT OFFICE CERTIFICATE -OF CORRECTION I Patent No. 3,775,73 v Dated v m 7, 1973 Inventor(s) Ernst Merl-cl It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet item jflthe inventor's name should read as follows: Ernst Mer'kl Signedand sealedthis B Oth d ay of April 197 (SEAL) At te s t EDWARD M .FLE'I' CHER JR v r C MARSHALL DANN Y Attesting Officer Commissioner of Patents 5 FORM PO-1050 (10 69) u 50316-PQ9 w u. s. covsnuuzrgr rigmrms omc: on o-au-au, 

1. In a lamp socket assembly, a combination comprising a housing at least a portion of which is made from an electrically insulating material, said housing comprising a substantially cylindrical hollow portion having an open end for receiving the base of a bulb, a transversal flange surrounding said cylindrical portion and having a supporting surface around said open end, at least two first resilient engaging means projecting from said supporting surface so as to engage the edge of a cutout into which said housing is introduced, and second resilient engaging means projecting from said surface; and electrically conductive carrier means engageable with said second engaging means and establishing electrical contact with one of the electrodes of the bulb whose base is received in said cylindrical portion.
 2. A combination as defined in claim 1, wherein said flange is provided at its supporting surface with an annular face removed a predetermined distance from said supporting surface to thereby form an annular ridge in the region of periphery of said flange.
 3. A combination as defined in claim 1, wherein said flange has a cut-out, and said conductive carrier means has a lug extending from one side of said flange to the other side thereof through said cut-out.
 4. A combinatioN as defined in claim 3, wherein said cut-out has a rectangular shape.
 5. A combination as defined in claim 1, further comprising protective cap means for covering said other end of said housing and releasably connected to the latter.
 6. A combination as defined in claim 5, wherein said flange has an annular face on the side of said supporting surface, said protective cap including resilient snapping means which snap over said flange and engage said annular face to thereby lock said cap to said housing.
 7. A combination as defined in claim 1, wherein said second resilient engaging means comprises at least two spaced tabs projecting from said supporting surface, each tab having a locking shoulder at its projecting end at a predetermined distance above said supporting surface; said housing further comprising at least two spacers in the region of said tabs and projecting from said supporting surface a distance approximately equal to said predetermined distance; and said conductive carrier means comprising a substantially flat annular ring operative to radially deflect said spaced tabs in response to passage of said ring over said locking shoulders and being held by said shoulders in abutment with said spacers once the ring passes the shoulders and is spaced said predetermined distance from said supporting surface.
 8. A combination as defined in claim 7, wherein said conductive carrier means further comprises two diametrically opposite supporting arms projecting from said annular ring toward said other end when said ring is held by said spaced tabs and said spacers, each supporting arm having at its projecting end a cutout for engaging a guide pin mounted on the base of the bulb.
 9. A combination as defined in claim 7, wherein said spacers are positioned on said supporting surface in the region of said supporting arms of said locked ring, each spacer engaging a respective arm to thereby prevent the latter from being deflected in a radial direction.
 10. A combination as defined in claim 1, wherein said cylindrical portion has another end spaced from said open end; and further comprising electrical contact means arranged at the other end of said cylindrical portion and contacting the other electrode of the bulb whose base is received in said cylindrical portion.
 11. A combination as defined in claim 10, wherein said electrical contact means comprises a conductive plug movable axially in relation to said other end of said cylindrical portion; limiting means for confining said conductive plug to axial movement between two positions; biasing means for urging said conductive plug to one of said positions, said conductive plug being held in a further position intermediate said two positions in response to engagement of said conductive plug with said other electrode of the bulb whose base is received in said cylindrical portion.
 12. A combination as defined in claim 11, wherein said housing includes abutment means at said other end of said cylindrical portion; said limiting means including a transverse holding member connected to said conductive plug, and said biasing means comprising a helical spring compressed between said abutment means and said transverse holding member.
 13. A combination as defined in claim 11, wherein said conductive plug is in the shape of a flat plate having spaced projections, and wherein said limiting means comprises a central slotted portion made from electrically insulating material, said plate being slidably mounted in the slot of said slotted portion, and said projections permitting said plate to slide between two axial positions in said slot. 